Amoebas survive environmental stress by differentiating into encapsulated cysts. As cysts, pathogenic amoebas resist antibiotics, which particularly counteracts treatment of vision-destroying Acanthamoeba keratitis. Limited genetic tractability of amoeba pathogens has left their encystation mechanisms unexplored. The social amoeba Dictyostelium discoideum forms spores in multicellular fruiting ...

Infections caused by Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris occur throughout the world and pose many diagnostic challenges. To date, at least 440 cases of severe central nervous system infections caused by these amebas have been documented worldwide. Rapid and specific identification of these free-living amebas in clinical samples is of crucial importance for efficien...

lesions in 1 week. Noncompliance with oral medications during October 1995 was associated with the appearance of new skin lesions. A new multidrug regimen was started in December 1995 with the combination of itraconazole (400 mg/d orally) and pentamidine (150 mg/d for 5 days and then 300 mg/d for 6 days intramuscularly). No improvement was observed. The initial therapeutic regimen (5fluorocytos...

Amebas of Dictyostelium discoideum contain both microfilaments and microtubules. Microfilaments, found primarily in a cortical filament network, aggregate into bundles when glycerinated cells contract in response to Mg-ATP. These cortical filaments bind heavy meromyosin. Microtubules are sparse in amebas before aggregation. Colchicine, griseofulvin, or cold treatments do not affect cell motilit...

Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxica...

While Amoeba proteus has long been the subject of extensive cytological and cytochemical studies, investigations with the electron microscope have been limited principally to the nuclear membrane (1-3). The observations reported herein were made in the course of studies intended to correlate cytochemistry (4) with knowledge of fine structure obtained with the electron microscope. I t is felt th...

Introduction. Naegleria fowleri, a free living amoeba, can cause devastating and deadly diseases in humans. This is the first report of primary amoebic meningoencephalitis from Iran. Case report. A five-month-old male infant presented with the history of fever and eye gaze for three days, after beginning of bacterial meningitis, a plain and contrast CT revealed communicated hydrocephalus. In th...

Legionella pneumophila expresses pili of variable lengths, either long (0.8 to 1.5 microm) or short (0.1 to 0.6 microm), that can be observed by transmission electron microscopy. We have identified a gene in L. pneumophila with homology to the type IV pilin genes (pilEL). An insertion mutation was constructed in pilEL and introduced into the L. pneumophila wild-type strain by allelic exchange. ...

All organs of the immune system are innervated and almost all neurotransmitter receptors are present on immune cells. We studied the effects of sympathetic innervation in the development of amebic liver abscess (ALA) in rats. Our results showed that lack of sympathetic innervation promote a decrease in size of ALA. We found scarce amoebas, increased the number of neutrophils and a few collagen ...

A panel of monoclonal antibodies was raised from mice immunized with a membrane preparation from Entamoeba histolytica, the pathogenic species causing invasive amebiasis in humans. Antibody EH5 gave a polydisperse band in immunoblots from membrane preparations from different E. histolytica strains, and a much weaker signal from two strains of the nonpathogenic species Entamoeba dispar. Although...